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BULLETIN  No.  144 


■^ibra 


ry 


JUNE,  1913 


AGRICULTURAL 
EXPERIMENT  STATION 


SOUTH  DAKOTA  STATE  COLLEGE  OF  AGRICULTURE 
AND  MECHANIC  ARTS 


DAIRY  HUSBANDRY  DEPARTMENT 


Preliminary  Report  on  the 
MILKING  MACHINE 


BROOKINGS,  SOUTH  DAKOTA 


The  Mitchell  Publishing  Company,  Mitchell,  S.  D. 


GOVERNING  BOARD 


Hon.  A.  E.  Hitchcock,  President Mitchell,  S.  D. 

Hon.  T.  W.  Dwight,  Vice  President Sioux  Falls,  S.  D. 

Hon.  A.  M.  Anderson Sturgis,  S.  D. 

Hon.  August  Prieberg  Beresford,  S.  D. 

Hon.  H.  Reinhardt Eureka,  S.  D. 


STATION  STAFF 

T.  W.  Dwight  Regent  Member 

A.  M.  Anderson Regent  Member 

Robert  L.  Slagle  President  of  College 

James  W.  Wilson Director  and  Animal  Husbandman 

N.  E.  Hansen Vice  Director  and  Horticulturist 

James  H.  Shepherd  Chemist 

E.  W.  Olive Botanist 

E.  L.  Moore Veterinarian 

C.  Larsen  Dairy  Husbandman 

A,  H.  Hume Agronomist  and  Superintendent  of  Sub-Stations 

J.  G.  Hutton Assistant  Chief  of  Agronomy 

S.  Garver Crops,  Detailed  by  U.  S.  Department  of  Agriculture 

M.  Chaplin Assistant  in  Agronomy  and  Collaborator 

I.  S.  Oakland  Assistant  in  Crops 

Howard  Loomis Agronomy  Analyist 

J.  N.  Fuller Assistant  and  Dairy  Bacteriologist 

D.  E.  Bailey Dairy  Analyst 

Howard  W.  Gregory Assistant  Dairyman 

C.  L.  Pier Assistant  Dairyman 

Guy  E.  Youngberg First  Assistant  in  Chemistry 

T.  B.  Kelly Assistant  Veterinary  Medicine 

R.  A.  Larson Secertary  and  Accountant 

W.  W.Powell Bulletin  Clerk  and  Stenographer 


CONTENTS 


5'cj  ly 


f><^ 


I.  Introduction 

,11.  Chief  Parts  of  Milking  Machine 

1.  The  pail  and  pulsator 

2.  The  collapsible  teat  cups 

3.  Vacuum  pipes 

4.  Vacuum  tank 

5.  Vacuum  pump 

6.  Power 

7.  Cost  of  a two-machine  outfit 

III.  Operatmn  of  the  Milking  Machine 

1.  Breaking  the  cows  . 

2.  Attaching  the  teat  cups 

3.  Condition  of  cows’  teats 

4.  Speed  of  pulsator 

5.  Detaching  the  teat  cups 
().  Stripping  the  cows 

IV.  Effect  of  Milking  Machine  on  yield  of  Milk  and  But- 

terfat.  ^ 

V.  Sanitary  Condition  of  IMachine-milked  Milk  vs.  Iland- 
milked  Milk. 

1.  Visible  impurities 

2.  Bacteria  or  germ  content 

a.  Normal  conditions 

b.  Use  of  sodium  chloride  or  common  salt 

c.  Use  of  2V2  per  cent  formalin  solution 

d.  Use  of  calcium  chloride  brine 

e.  Use  of  Cotton  filter 

VI.  Summary 


Preliminary  Report 
On  Milking  Machines. 


C.  Larsen,  Wm.  White  and  J.  W.  Fuller. 


INTRODUCTION. 

With  a view  of  testing  the  practicability  of  the  milk- 
ing machine,  the  South  Dakota  experiment  station,  two 
years  ago  last  February,  installed  the  Hazelwood  milking 
machines  in  the  college  dairy  barn.  These  machines,  with 
the  exception  of  one  day  out  of  each  month  when  the  ma- 
chine-milked cows  were  milked  by  hand,  and  also  in  a few 
instances  when  the  gasoline  engine  used  for  power  under- 
went repairs,  have  been  in  continuous  operation  since  that 
time,  or  for  nearly  two  and  one-half  years.  The  cov  s were 
milked  by  hand  one  day  of  each  month  to  ascertain  the  ap- 
proximate production  of  individual  cows.  The  Hazelwood 
machine  milks  two  cows  at  a time,  and  has  no  partition  in 
the  pail.  Two  machines  were  installed,  as  one  man  can 
attend  to  two  as  well  as  to  one. 

The  data  on  hand  at  the  present  time  are  not  com- 
plete, but  on  account  of  the  demand  for  information  re- 
garding milking  machines,  this  preliminary  report  giving 
the  results  to  date  with  this  particular  make  of  milking 
machine  is  issued. 

CHIEF  PARTS  OF  MILKING  MACHINE 

THE  PAIL  AND  PULSATOR 

The  pail  includes  the  cover,  the  pulsator,  and  the  rub- 
ber tubing  contnecting  the  pail  with  the  vacuum  pipe  and 
with  the  teat-cups. 


206 


Tile  pail  is  conical  in  shape,  wide  at  the  bottom  and 
narrow  at  the  top.  It  is  somewhat  heavier  in  structure 
than  the  average  tin  pail.  This  is  necessary  to  withstand 
the  greater  outside  air  pressure  when  the  machine  is  in 
operation.  The  vacuum,  or  suction  on  the  inside  of  the 
pails,  is  equal  to  about  one-half  atmosphere  or  nearly  seven 
and  one-half  pounds.  The  capacity  of  the  pail  is  about 
fifty-six  pounds.  The  pail,  however,  will  hold  only  about 
foirty-seven  pounds,  as  the  milk  will  be  drawn  into  the 
vacuum  connections  if  entirely  filled.  The  capacity  is  not 
great  enough  for  two  of  the  heaviest  milking  cows.  Pail 
capacity  was  lacking  in  the  case  of  the  two  Holstein. cows 
milked  together.  These  cows,  however,  are  unusually 
heavy  milkers  during  the  first  part  of  their  lactation  period. 

The  cover  fits  on  the  top  of  the  pail  like  a lid.  A 
rubber  ring  acts  as  a cushion  between  the  top  of  the  pail 
and  the  under  part  of  the  cover.  As  soon  as  a vacuum  is 
created  in  the  pail,  the  cover  is  tightly  drawn  against 
the  edge  of  the  pail,  making  it  entirely  air  tight.  When 
the  suction  in  the  pail  is  released  the  cover  with  all  of 
its  attachments  can  be  easily  removed. 


207 


,ici  • ’ , 

t « 


Cross-section  view  of  the  Hazelwood  Milking  Machine. 


208 


The  pulsator  is  a small,  cylindrically-shaped  device, 
two  and  one-fourth  inches  in  diameter,  and  four  and  one- 
half  inches  high.  One  end  of  it  snugly  fits  into  a socket 
or  opening  on  the  top  and  in  the  center  of  the  cover.  It 
operates  similar  to  an  engine  cylinder.  This  pulsator  op- 
erates by  vacuum,  and  not  by  pressure.  As  isoon  as  the 
vacuum  is  generated  in  the  pail,  the  head,  inside  of  the 
cylinder  begins  to  move  up  and  down.  An  attachment 
extends  through  the  wall  of  the  cylinder,  and  moves  up 
and  down  in  a slot  in  the  cylinder  wall.  This  attachment 
is  coinected  with  a small  plunger,  which  in  turn  releases 
and  brings  on  the  suction.  This  alternate  suction  and 
release  cause  the  pulsaition.  Milking  machines  having 
constant  suction  have  been  found  to  give  unsatisfactory 
results. 

In  a few  instances,  during  real  cold  weather,  the 
pulsator  did  not  work  well.  This  perhaps  was  the  fault 
of  the  operator  more  than  of  the  milking  machine.  By 
using  thin  machine  oil,  no  more  trouble  was  encountered 
from  this  source. 

The  tubing  connecting  the  pail  with  the  vacuum  pipe 
is  made  of  heavy  black  rubber.  This  tubing  does  not  come 
in  touch  with  any  milk,  except  when  the  pail  is  too  full 
and  some  milk  is  drawn  from  the  pail.  It  is  therefore 
easy  to  keep  in  condition  and  does  not  easily  wear  out. 

The  rubber  tubes  connecting  the  teat-cups  with  both 
sides  of  the  pail  are  exposed  to  harder  use.  Each  of  these 
tubes  is  about  four  feet  in  length,  with  an  opening  of  about 
one-half  an  inch  in  diameter.  They  naturally  require  con- 
siderable care  in  order  to  keep  them  sanitary  and  to  pro- 
long their  life.  Two  sets  of  tubes  have  been  used  during 
the  nearly  two  and  one-half  years  the  machines  have  been 
in  operation.  They  are  made  of  heavy  rubber  to  prevent 
the  walls  from  caving  in  when  the  suction  is  applied. 
When  not  in  use  they  hang  on  hooks  on  each  side  of  the 
pail  cover. 


209 


THE  COLLAPSIBLE  TEAT-CUPS 

There  are  two  sets  of  teat-cups  to  one  pail,  thus  mak- 
ing one  set  of  four  for  each  of  opposite  sides  of  pail. 
When  connected  and  ready  for  milking,  they  terminate 
the  rubber  tubes  mentioned  in  preceding  paragraph  and  fit 
on  to  the  cow^s  teats.  Two  cows  can  thus  be  milked  at 
the  same  time  with  one  pail  or  machine.  These  teat-cups 
are  made  of  rubber.  They  are  conical  in  shape,  being 
wider  at  the  top  than  at  the  bottom.  They  are  about  one 
and  one-half  inches  in  diameter,  and  three  and  one-hal^ 
inches  long. 

The  wall  on  one  side  of  the  teat-cups  is  made  of  heavy 
rubber,  thus  insuring  a stiff,  almost  non-flexible  wall. 
The  wall  on  the  opposite  side  of  the  teat-cup  is  made  of 
thinner  and  more  fiexible  rubber.  This  construction  per- 
mits one  side  to  collapse  against  the  side  of  the  cow’s 
teat  each  time  there  is  a pulsation.  This  action  of  the 
teat-cup  comes  nearer  imitating  a calf’s  sucking  than 
any  other  teat  cup  ever  tried  by  the  investigators.  Cows 
with  sore  teats  can  be  milked  very  easily  with  such  a 
teat-cup.  One  of  the  cows  on  the  milking  machine  ac- 
cidentally had  a deep  gash  cut  diagonally  across  the  teat. 
By  placing  the  stiff  side  of  the  teat-cup  over  the  wound, 
she  was  milked  without  trouble,  and  the  wound  healed 
in  a short  time.  To  milk  this  cow  by  hand  would  have 
been  almost  impossible. 


210 


Cross-sectional  view  of  the  collapsible  rubber  teat-cup,  showing  its  action 
when  in  operation  during  one  complete  pulsation. 


211 


On  the  inside  of  the  teat-cup  there  is  a sleeve  or  a 
tubing  extending  into  the-  teat-cup  from  the  top.  This 
tube  extends  into  the  teat-cup  almost  as  far  as  the  length  of 
the  average  cow’s  teats'.  It  is  not  quite  as  large  in  diameter 
as  is  the  teat-cup  itself.  A space  is  left  between  the 
wall  of  the  sleeve  and  the  wall  of  the  teat-cup,  thus  per- 
mitting the  suction  to  extend  up  on  the  side  of  the  teat. 
Such  a construction  causes  one  side  of  the  cup  to  col- 
lapse and  press  on  the  side  of  the  teat.  This  sleeve  is 
about  one  and  three-fourths  inches  long. 

Teat-cups  with  two  kinds  of  sleeves  have  been  in 
use.  One  kind  has  a full  opening  at  the  lower  end  of 
the  sleeve,  while  the  second  kind  has  only  a small  opening 
in  the  end.  The  latter  kind  does  not  stay  on  the  teats 
’ so  well  as  do  the  cups  having  the  large  opening. 

VACUUM  PIPES 

The  vacuum  pipes  runiiiiig  in  front  of  the  cows  are 
ordinary  one-inch  piping,  and  are  connected  Avith  (the 
vacuum  pump  in  the  engine  room.  They  Avere  installed 
by  a local  plumber.  lletAveen  every  other  coav  there  is  a 
stop-c(^ck  in  the  vacuum  pipe.  During  the  milking  period, 
the  rubber  tube  previously  mentioned,  connects  the  pail 
AA’ith  this  cock. 

At  the  remote  end  of  the  vacuum  i)ipe  there  is  a 
guage  and  a safety  valve.  The  safety  valve  can  be  set  to 
admit  air  Avhen  a certain  vacuum  has  bfcen  obtained. 
This  obviates  all  danger  of  applying  too  much  suction  in 
the  teat-cups. 


212 


Inside  view  of  Dairy  barn  showing  the  manner  in  which  the  milking  plant  was  installed. 


218 


VACUUM  TANK 

The  vacuum  tauk  is  placed  between  the  vacuum  pump 
and  the  vacuum  pipes  and  near  the  former.  This  tank 
serves  two  purposes : first,  to  make  the  suction  more  un- 
iform ; and  second,  as  a vacuum  supply  tank.  It  is  made 
of  galvanized  iron  and  has  a cubical  content  of  about  8.16 
cubic  feet. 


VACUUM  PUMP 

The  vacuum  is  generated  by  means  of  an  ordinary 
rotary  air  pump.  The  pump  installed  was  too  small  in 
size  to  supply  regularly  the -needed  vacuum  for  two  ma- 
chines or  pails.  Most  of  the  time  it  was  necessary  to  op- 
erate with  about  twelve  inches  of  vacuum  instead  of  with 
fifteen,  the  latter  being  the  proper  amount.  Because 
of  this  low  vacuum,  and  on  acount  of  experimenting  with 
differently  constructed  teat-cups,  some  difficulty  was  en- 
countered with  the  teat-cups  falling  off  during  the  milking 
process'.  ■ 

POWER  USED 

A twelve  horse  gasoline  engine  is  used  for  running 
the  vacuum  pump.  This  engine  is  much  larger  than  is 
necessary,  and  was  installed  with  a view  of  also  running 
a feed  grinder.  It  is  now  the  intention  to  install  an  elec- 
tric plant  and  generate  and  store  electricity  during  milk- 
ing hours.  This  to  some  extent  will  overcome  the  loss  in-, 
cident  to  the  use  of  so  large  an  engine  for  operating  the 
milking  machines.  • , . 


214 


View  of  Hazelwood  milking  machine  and  showing  the 
manner  of  draining  and  hanging  the  various  sized 
teat-cups  when  not  in  use. 


215 


Cost  of  Milking  Outfit 

The  cost  of  two  pails  with  pulsator,  teat-cups  and  rub- 
ber tube  connection  is  about  |200.  The  cost  of  vacuum 
pump,  vacuum  tank  and  vacuum  pipes  with  stop-cocks  is 
about  $100.  The  cost  of  a milking  machine  plant  without 
the  power  is  therefore  about  $300.  One  man  with  such  an 
outfit  can  milk  about  25  cows  in  one  hour. 

OPERATION  OF  THE  MILKING  MACHINE 
In  the  month  of  February,  1911,  ten  fresh  cows  were 
put  on  the  milking  machine.  Two  of  these  cows  were 
pure- bred  Holstein  Friesians  giving  a darge  quantity  of 
jnilk;  four  of  them  were  Jersey  cows  giving  a medium  flow 
of  rich  milk;  two  of  them  were  pure-bred  Shorthorn  cows 
giving  a small  amount  of  milk;  and  two  were  common 
grade  cows  giving  only  a small  flow  of  milk. 

Breaking  the  Cows  to  Milking  Machine 
These  cows  were  easily  broken  to  the  use  of  the 
milking  machine.  Some  of  them,  however,  became  ac- 
customed to  it  more  readily  than  others.  Briefly,  it  may 
be  stated  that  the  more  milk  the  cows  gave  the  easier  it 
was  to  get  them  used  to  the  milking  machine.  Two  more 
cows  were  started  on  the  milking  machine,  but  one  of 
tliese  two  absolutely  refused  to  be  Inilked  by  it.  The  ex- 
pert representing  the  milking  machine  company  tried  for 
about  three  weeks  to  milk  this  cow  but  finally  was  obliged 
to  give  up.  Apparently  she  did  not  care  much  for  the  ac- 
tion of  the  teat-cups,  but  the  clicking  noise  of  the  pulsator 
at  her  side  was  a great  annoyance  to  her.  As  soon  as  the 
machine  began  to  operate  she  would  turn  her  head  to  one 
side,  look  excitedly  at  the  pail,  and  then  kick.  This  she 
continued  until  the  pulsator  was  stopped.  The  milking 
expert  stated  that  in  all  of  his  experitence  this  was  the 
only  cow  that  had  refused  to  be  milked  by  the  machine. 
In  explanation  of  this  it  may  be  stated  that  this  cow  was 
a three-year-old  grade.  Some  Hereford  and  Red  Poll 
blood  was  represented  in  her.  She  was  also  difficult  to 
break  to  hand-milking. 


216 


View  showing  the  Hazelwood  milking  machine  in  operation,  milking  cows  1 and  2 in  table. 


217 


The  pure-bred  Shorthorn  cows  and  the  grade  cows 
regarded  the  milking  machine  with  suspicion  for  about 
one  week,  after  which  time  they  were  perfectly  at  ease 
during  the  milking  process.  The  Holsteins  and  Jerseys 
apparently  accepted  the  machine  as  a matter  of  course. 
They  readily  gave  down  their  milk  from  the  beginning. 

Whether  or  not  a cow  gives  down  her  milk  for  the 
milking  machine  during  its  first  usage  depends  on  the 
milker  and  on  the  individuality  of  the  cow.  When  the 
milking  machine  is  first  used  the  operator  should  be  the 
herdsman  or  a man  with  whom  the  cow^s  ajrie  acquainted. 
If  this  strange  machine,  with  a strange  operator  attempts 
to  do  the  milking,  the  cows  will  be  much  more  suspicious 
and  even  afraid,  than  if  the  regular  attendant  accom- 
panies the  milking  machine.  The  regular  herdsman  knows 
the  temperament  of  the  different  cows,  and  he  can  ap- 
proach each  cow  sympathetically.  By  gently  handling 
the  cow’s  teats  and  udder  she  gives  down  milk  before  the 
milking  machine  is  attached.  The  teat  cups  are  then  put 
on  and  the  milk  is  extracted  before  the  cow  realizes  what 
did  it.  As  soon  as  the  cows  had  been  milked  a few  times 
with  the  machine  no  difficulties  were  encountered  by 
reason  of  any  of  the  cows  refusing  to  give  down  their 
milk. 

The  individuality  of  the  cow  needs  to  be  considered 
in  this  connection.  One  of  the  writers  demonstrated  the 
operation  of  the  milking  machine  on  the  stage  before  a 
gathering  of  about  1800  people.  The  cow  used  in  the 
demonstration  had  never  seen  a milking  machine  before, 
yet  she  readily  gave  down  her  milk.  She  was  an  intelli- 
gent appearing,  high  grade  family  Jersey  cow,  used  to  be- 
ing handled,  and  giving  a large  flow  of  milk.  She  was  do- 
cile, gentle,  and  had  implicit  confidence  in  people. 

Generally  speaking,  it  may  be  said  that  the  cows  of 
the  dairy  breeds,  which  yielded  a fairly  large  flow  of  milk, 
readily  gave  down  their  milk  from  the  very  beginning.  The 
cows  which  had  more  or  less  of  the  range-cattle  blood  in 


218 


them,  and  which  ^ave  only  a small  flow  of  milk,  needed 
to  be  handled  with  tact  and  understanding  during  the 
first  week  to  obtain  the  best  results  from  the  use  of  the 
milking  machine. 

Attaching  the  Teat-cups 

Some  experience  is  necessary  before  the  operator  can 
properly  attach  the  teat-cups.  In  the  first  place  the  opera- 
tor should  use  care  to  allow  as  little  barn  air  as  possible 
to  enter  the  cups  while  there  is  vacuum  in  the  pail,  thus 
a lowing  dust  and  organisms  to  enter.  During  the  attach- 
ment of  the  teat-cups  the  barn  air  is  prevented  from  enter- 
ing the  pail  by  bending  the  rubber  tube  between  the  teat- 
cup  and  the  connector.  By  using  care,  and  with  a little 
experience  practically  no  barn  air  need  to  be  drawn  into 
the  pail. 

If  the  teat-cups  are  not  properly  attached  they  are 
more  likely  to  fall  off  during  the  last  part  of  the  milking 
period  when  the  udder  is  limp. 

Condition  of  Cows^  Teats 

Before  the  cups  are  attached  to  the  teats  the  operator 
should  see  that  the  teats  are  in  proper  condition  and  that 
they  enter  the  teat-cups  straight  without  being  turned  and 
twisted. 

The  teats  of  the  cows  are  not  always  in  equally  good 
condition  to  be  milked  by  the  machine.  If  the  cows  have 
been  exposed  to  damp  and  cold  surroundings,  the  teats 
are  short,  and  the  covering  of  the  teats  is  curled  and  con- 
tracted. When  the  teats  are  in  such  a condition  it  is  im- 
portant that  the  operator  brings  them  into  normal  condi- 
tion before  the  teat-cups  are  attached.  This  can  be  done  by 
gently  rubbing  and  slightly  pulling  the  teats  with  the 
warm  hands  of  the  milker.  The  teats  should  be  clean  be- 
fore the  teat-cups  are  attached.  Unclean  teats  are  usually 
contracted  as  mentioned  above,  and  contaminate  the  milk. 


219 


Such  contracted  teats  milk  Avitli  difficulty.  The  teat- 
cups  do  not  get  a firm  grip  nor  a good  symmetrical  hold 
and  they  are  likely  to  give  trouble  by  falling.  As  a result 
one  side  of  the  teat  may  be  pulled  into  normal  length  be- 
fore the  other,  and  thus  cause  the  end  of  the  teat  to  turn 
and  partially  prevent  the  proper  discharge  of  the  milk. 

In  this  experiment  the  cows  were  kept  out  doors  in 
a yard  during  the  day,  except  in  stormy  and  cold  days. 
At  night  the  cows  were  kept  in  the  barn  except  during  the 
warm  summer  months. 

The  milking  machine  was  found  to  need  less  atten- 
tion during  the  morning  milking,  than  it  did  at  night.  The 
poorer  condition  of  the  cows’  teats  in  the  evening  was 
found  to  be  the  cause.  In  the  morning  the  teats  of  the 
cows  were  usually  warm  and  normal  in  shape.  In  such  a 
condition  it  is  easier  for  the  operator  to  properly  attach 
the  teat  cups. 

Speed  of  I^ulsator 

No  rules  can  be  laid  down  for  governing  the  speed  of 
the  pulsator  for  the  different  cows.  The  speed  of  the  pul- 
sator  will  vary  with  the  size  of  the  teats  and  to  some  ex- 
tent with  the  ease  or  difficulty  with  which  the  cows  milk, 
and  the  manner  in  which  tlie  cow  gives  down  her  milk. 

An  easy  milking  cow  permits  of  a tritle  higher  speed 
of  the  pulsator  than  does  a hard  milking  cow.  This  is  in 
accord  Avitli  reason.  When  the  pulsator  works  at  high 
speed  the  suction  period  is  sliort.  This  does  not  give 
enough  time  for  the  milk  in  the  teat  to  be  extracted  from 
a hard  milking  cow.  This  rapid  alternate  release  and  suc- 
tion of  a hard  milking  cow  results  in  slow  milking.  With 
a short  teated  and  easy  milking  cow,  the  pulsator  can  be 
operated  faster,  and  at  about  110  strokes  per  minute. 
With  a medium  hard  milking  cow  around  90  strokes  per 
minute  is  about  proper.  The  speed  of  the  pulsator  can 
also  be  greater  with  a cow  giving  a large  flow  of  milk 
than  Avith  one  giving  a small  flow.  The  former  usually 
gives  down  her  milk  faster. 


220 


View  showing  normal  and  ideal  condition  of  cows  teat.  In  this  condition 
the  teat-cups  can  be  properly  attached. 


221 


View  of  the  same  cow’s  teats  as  shown  on  opposite  page.  This  view  was 
taken  after  the  cow  had  been  exposed  to  wet  and  cold  conditions.  If  the 
teat-cups  are  attached  to  teats  while  in  this  abnormal  condition  they  are 
likely  to  fall  off. 


222 


During  the  latter  part  of  the  milking  or  during  the 
stripping  period,  the  speed  of  the  pulsator  may  be  slight- 
ly reduced.  In  a short  time  an  observing  operator  gets 
used  to  the  cows  and  to  the  machine,  and  the  proper  speed 
of  the  pulsator  will  soon  be  learned. 

The  speed  of  the  pulsator  can  be  regulated  by  means 
of  a little  screw  on  the  pail  cover.  It  is  not  necessary 
to  adjust  it  every  time  the  vacuum  varies.  During  the 
change  of  the  pail  from  one  set  of  cows  to  the  other  there 
will  be  a slight  variation  in  the  amount  of  vacuum.  When 
the  teat-cups  are  detached  the  vacuum  rises  slightly,  and 
the  speed  of  the  pulsator  is  somewhat  increased.  When 
the  teat  cups  are  again  attached  to  two  other  cows  the 
vacuum  is  temporarily  slightly  lowered. 

The  vacuum  safety  valve  is  not  sufficiently  sensitive 
nor  is  the  vacuum  pump  of  sufficient  capacity  to  maintain 
an  exact  amount  of  vacuum  during  these  changes.  So  far 
as  learned  nothing  serious  results  from  a variation  of  the 
speed  of  the  pulsator.  However,  better  milking  results 
when  the  proper  speed  of  the  pulsator  is  maintained. 

DETACHING  THE  TEAT-CUPS 

When  the  operator  learns  the  action  of  the  milking 
machine  on  the  different  cows,  and  the  appearance  of  each. 
coAv’s  udder  wheini  full  and  empty,  he  can  tell  Avitbout 
much  Avatching  when  the  milking  is  completed.  An  inex- 
perienced operator  should  watch  the  glass  bulbs  or  inspec- 
tion glasses  at  the  bottom  of  each  teat-cup.  When  the  milk 
stops  flowing  into  these  glass  bulbs,  probably  the  coav  is 
dry.  The  fact  that  the  milk  has  stopped  floAving  is  not  a 
sure  indication  that  the  cow  is  milked  dry.  Occasionally 
the  teat  will  get  into  such  a position  that  the  milking  can 
not  be  completed.  Before  the  teat-cups  are  detached,  the 
operator  should  gently  pull  on  them  to  slightly  displace  the 
teat.  If  there  is  any  more  milk  in  the  udder,  it  will  then 
be  extracted.  When  the  operator  is  satisfied  that  there 
is  no  more  milk  in  the  udder,  the  vacuum  is  shut  off  with 
one  hand,  and  with  the  other  hand  the  teat  cups  are  re- 
moved. 


223 


Stripping  the  Cows 

In  this  experiment  the  milking  machine  was  not  re- 
lied on  to  do  the  strippings  As  soon  as  the  teat  cups  were 
detached,  the  milk-  was  stripped  by  hand  into  the  teat 
cups.  Usually  no  more  milk  was  obtained  than  the  tube 
and  cups  would  hold.  When  the  stripping  was  completed 
the  milk  was  let  into  the  pail  by  opening  the  stop-cock.  In 
some  instances  practically  no  milk  was  obtained,  while  in 
other  cases  one  or  more  of  the  teats  yielded  more  than 
should  be  left  in  the  cow’s  udder. 

Some  recommend  that  one  man  attend  to  the  milking 
machine  and  another  do  only  the  stripping.  By  this 
method  the  man  who  does  the  stripping  may  not  get  to 
strip  the  cow  till  some  time  after  the  milking  machine  has 
done  its  work.  This  interval  of  time  may  cause  the  cow 
to  take  the  milk  again.  It  may  be  the  means  of  drying  up 
the  cow,  and  it  may  cause  diseased  udders. 

When  the  milking  of  a cow  once  has  started,  it  should 
be  continued  without  intermission.  For  this  reason  all 
the  cows  were  stripped  as  soon  as  the  teat  cups  were  de- 
tached. 

EFFECT  ON  YIELD  OF  MILK  AND  BUTTERFAT 

It  is  very  difficult  to  secure  data  which  may  safely  be 
regarded  as  an  index  to  tlie  effect  of  a milking  machine  on 
the  yield  of  milk  and  butterfat.  One  cow  can  not  be  com- 
pared with  another  as  there  is  so  much  difference  in  the 
individuality  of  the  different  cows.  The  yield  during  a 
definite  period  by  machine  cannot  be  compared  with  the 
yield  from  another  period  of  e(iual  length  by  hand  in  the 
same  lactation  period  of  the  same  cow,  since  alternating 
from  machine  to  hand  milking  and  vice  versa  is  too  dis- 
turbing and  unnatural  to  the  cow. 

In  this  experiment  the  yield  of  the  same  cows  while 
milked  by  hand  during  the  lactation  period  preceding  the 
milking  machine,  has  been  compared  with  the  yield  during 
the  succeeding  lactation  period  with  the  milking  machine. 
Several  disturbing  factors  enter  in  to  make  even  this  com- 


224 


parison  unreliable.  Tbe  length  of  the  succeeding  lactation 
periods  of  the  same  cows  can  not  be  entirely  controlled,  due 
to  the  failure  of  some  cows  to  conceive  when  mated.  It 
is  a well  known  fact  that  most  cows  have  an  lacta- 

tion period.  The  difference  in  age  also  makes  it  difficult 
to  compare  the  yield  of  one  lactation  period  with  that  of 
another  period. 

The  following  table  shows  the  amount  of  milk  and 
butterfat  given  by  each  two  cows  during  the  lactation  per- 
iod when  milked  by  hand,  and  the  two  succeeding  lactation 
periods  when  milked  with  the  milking  machine. 


Lactation  period  previous  to  ^ ^ 

n«p  of  Tniikinp-  mpphinp  First  lactatiOD  period  on  Second  lactation  period 

(h^d  mnk?d)  milking  machine  on  milking  machine 


: 225 


(sXup)  poijod  uo^u:^ 
-Dui  JO  LijSuai  -Av 


juj  JO  spunoj 


;^J 

JU0O  Jed  'AY 


spunod 


(SiCup)  pouad  uoijuj 

-oui  JO  qjSuai  -Ay 


juj  JO  spunoj 


J^J 

juaa  jad  *ay 


^nra  JO 

spunoj 


(s^Cnp)  pouad  uoijbj 

-oni  JO  qjSnai  'av 


juj  JO  spimoj 


JBj 

juao  jad  -av 


illiui  JO 

spunoj 


(M 

•a 

a 

03  Cd 

I- 

S5o 


'CJ 

a 

03  90 
(D  CO 

“ s 

0)  o 

o 


«o  00 

^ T3 

d ® PI 

d 2 

03  la  2 o- 

^ 5 

O 03  Y 03 

c:»  o» 

5 o o 

MO 


-a  p 

d ^ 
fH  O 

O O 


''No.  3 we  were  unable  to  get  in  calf,  which  probably  accounts  for  the  increased  production. 

■fNo  57  was  substituted  for  No.  3.  The  latter  cow  we  were  unable  to  get  in  calf. 

JNo.  8 is  not  included  as  she  is  a heifer  and  had  no  hand-milked  lactation  period  before  she  was  put  on  the  milk- 
ing machine. 


226 


The  average  production  of  each  cow  per  day  during 
the  hand  milked  period  was  19.9  pounds  of  milk  and  0.82 
pounds  of  butterfat.  During  the  first  period  with  the 
milking  machine  the  same  cows  produced  on  an  average 
per  COW,  per  day,  22  pounds  of  milk  and  0.92  pounds  of 
butter  fat.  The  increased  age  of  four  of  the  cows  and  the 
fact  that  cow  No.  3 did  not  get  in  calf  undoubtedly  account 
for  the  slightly  higher  results. 

During  the  following  period  when  the  milking  ma- 
chine was  in  use  the  average  production  per  cow  per  day  was 
23  pounds  of  milk  and  0.96  pounds  of  butter  fat.  These  av- 
erages include  the  production  of  cow  No.  57  instead  of  cow 
No.  3.  The  latter  cow  was  eliminated  on  account  of  not 
being  in  calf.  The  substitute  cow  No.  57  is  also  a Jersey 
cow,  and  in  production  she  about  equals  No.  3 while  in 
normal  condition. 

The  number  of  cows  and  the  length  of  period  they 
have  been  milked  by  the  milking  machine,  do  not  warrant 
drawing  any  conclusions  as  to  the  effect  of  the  milking 
machine  on  the  persistency  of  milk  production  and  the 
amount  of  milk  and  butterfat  produced.  It  is  quite  safe, 
however,  to  conclude  that  the  daily  yield  of  milk  and  but- 
terfat is  not  affected  by  the  use  of  the  milking  machine, 
when  properly  operated. 

In  these  experiments  the  data  and  observations  indi- 
cate that  cows  producing  a small  quantity  of  milk,  say 
less  than  3000  pounds  during  a lactaiton  period,  have  their 
lactation  period  slightly  shortened  by  the  use  of  the  milk- 
ing machine.  The  results  of  the  use  of  the  milking  machine 
also  indicate  that  the  lactation  period  of  large  producing 
cows  is  prolonged.  It  was  found  difficult  to  dry  up  per- 
sistent milk  producers  when  the  cows  were  milked  by  ma- 
chine. 


227 


SANITARY  CONDITION  OP  MACHINE-MILKED 
MILK  vs.  HAND-MILKED  MILK 

In  considering  the  sanitary  condition  of  milk,  two  fac- 
tors need  to  be  considiered : 

First,  the  visible  impurities.  ' ' 

Second,  the  number  of  bacteria  or  germs. 

Visible  Impurities 

The  machine  milked  milk  was  at  all  times  remarkably 
free  from  visible  impurities.  The  machine-pail  is  closed  dur- 
ing the  milking  process.  There  is  no  opening  large 
enough  to  admit  the  entrance  of  any  foreign  matter  vis- 
ible to  the  naked  eyes.  The  possibility  of  obtaining  milk 
containing  sediments  of  any  kind  or  other  materi-^l  sus- 
pended in  the  milk  is  removed  almost  entirely  by  the 
use  of  the  milking  machioe. 

Bacterial  or  Germ  Content 

All  samples  of  milk  from  which  counts  were  made  in 
this  experiment  were  secured  at  the  barn  as  soon  as  the 
cows  had  been  milked.  In. the  case  of  milk  drawn  by 
hand,  the  sample  was  taken  from  the  pail  when  brought  into 
the  milk  room.  The  milk  room  is  near  the  stable.  Milk 
drawn  by  the  milking  machine  was  also  sampled  when 
brought  into  the  milk  room.  Tlie  samples  were  placed  in 
isterile  flasks  and  immediately  taken  to  the  laboratory,  and 
at  once  plated.  Lactose  agar  was  the  medium  used.  The 
plates  were  incubated  at  98  degrees  Fahrenheit  for  48 
hours,  then  counted.  A small  hand  lens  was  used  in 
counting. 


228 


TABLE  II. 


Showing  number  of  bacteria  in  milk  drawn  by  band  as 
compared  with  milk  drawn  by  the  milking  machine 


So 

D 

0,1  U 

o.^ 

y 

Syd 

KU 

.50 

d . 

M S y 

c S 

o y 

gSSfe 

-S  g ^ 

to  ^ . 

0)  y 

1 ""  >>» 

y >>  P- 

>.P 

X (-  <v  IV 
.2 

“C  ‘'3  ^ y 

o y y <p 

ra 

y c ^ d 

o y -2  y y 

'Eg'SS 

0/  d 

OhUSW 

i (D  vr  eO 
CUOSPQ 

PuM^pq 

<u 

(D  d r-  d 

cuicogm 

y o 

3,000 

l,215.000x 

305.000 

4 5,000“ 

2 9, “000 

3,500 

1,500 

520,000 

308,000 

60,000 

31,000 

4,000 

4.000 

720,000 

285,000 

80,000 

36,000 

9,500 

2,000 

710,000 

220,000 

25,000 

47,000 

6,800 

300 

4,800,000x 

200,000 

130,000 

13,000 

2,100 

1,500 

670,000 

285,000 

40,000 

20,000 

6,600 

1,100 

620,000 

185,000 

85,000 

260,000 

40,000 

2,100 

610,000 

430,000 

,90,000 

102,000 

65,000 

250 

450,000 

336,000 

80,000 

122,500 

130,000 

350 

420.000  1 

195,000 

100,000 

38,500 

100,000 

550 

830,000 

415,000 

85,000 

78,000 

280,000 

250 

550,000 

230,000 

115.000 

94,000 

45,000 

600 

510,000 

60,000 

50,000 

73,300 

800 

450,000 

125,000 

95,000 

900,000x 

3,000 

l,300,000x 

285,000 

40,000 

1 800,500x 

3,000 

550,000 

170,000 

40,000 

i 43  300 

2,000 

300,000 

195,000 

65,000 

43,500 

3,000 

190,000 

320,000 

17,000 

460,000 

110,000 

30,000 

530,000 

180,000 

13,000 

430,000 

2,600,000x 

! 

18,000 

490,000 

350,000 

20,000 

720,000 

l,210,000x 

23,000 

430,000 

450,000 

22,000 

460,000 

800,000 

12,000 

390,000 

340,000 

35.000 

390,000 

100,000 

1 

25,000 

390,000 

150,000 

1 

24,000 

600,000 

60,000 

1 

! 

12,000 

450.000 

70,000 

1 

11.000 

390,000 

400,000 

22,000 

426,000 

190,000 

18,000 

460,000 

320,000 

17,000 

630,000 

120,000 

16,000 

490,000 

160,000 

12,000 

600,000 

140,000 

13,000 

620,000 

300,000 

1 

15,000 

670,000 

290,000 

1 

Average 

10,739 

609,286 

252,166 

72,068 

134,070 

67,708 

“x” — Not  included  in  average.  Teat-cups  fell  off  into  bedding. 


229 


Normal  The  bacteriological  determination  in  periods 
Conditions  1 and  2 were  carried  out  at  the  same  time,  ex- 
tending over  a period  from  October  2nd  to 
December  11th. 

The  cows  were  kept  in  the  barn  during  nights,  and 
in  the  day  were  turned  out  into  a well  bedded  run -shed 
having  a clean  open  yard  in  connection  with  it. 

No  unusual  care  was  observed  in  the  case  of  hand  or 
machine  milking.  Partially  covered  pails  were  used  for 
hand  milking. 

The  teat-cups  and  rubber  tubes  were  cared  for  as  rec- 
ommended by  the  expert  who  installed  the  machine.  This 
consisted  of  rinsing  the  rubber  parts  in  two  sets  of  water 
every  evening  immediately  after  milking.  The  machine 
was  attached  to  a vacuum  pipe  extended  into  the  milk  room 
With  the  suction  turned  on,  the  tubes  aud  teat-cups  were 
raised  up  and  down  in  the  cold  water.  This  thoroughly 
rinsed  the  rubber  parts.  Every  morning  the  teat-cups  and 
rubber  tubes  were  thoroughly  cleaned  in  warm  water  con- 
taining some  Wyandotte  cleaning  powder  and  long  han- 
dled brushes  made  to  fit  tlie  rubber  tubing.  Then  ah  rub- 
ber parts  were  scalded  in  hot  clean  water,  and  hung  up  to 
drain  and  dry. 

Use  of  Sodium-  During  period  3 all  the  conditions  in 
chloride  or  com-  th©  barn  and  of  the  cows  and  their  sur- 
mofb  salt  ings  were  the  same  as  described  above, 

ed  above.  The  parts  of  the  milking  machine  were 
also  cleaned  as  described  above.  Instead  of  hanging  the 
rubber  parts  up  to  dry  between  milkings,  they  were  soak- 
ed in  a saturated  solution  of  sodium-chloride  or  common 
salt  during  the  intervals  between  milkings. 

Use  of  In  period  4 the  condition  of  the  cows,  of  the  barn 
formalin  surroundings,  and  the  care  of  the  parts  of  the 
milking  machine  were  as  described  under  period  1 and  2. 
The  only  difference  was  the  soaking  of  the  rubber  parts  in  a 
2%  per  cent  solution  of  formalin  between  milkings,  instead 
of  hanging  the  parts  up  to  drain  and  dry. 


230 


Calcium  In  period  5 the  teat-cups  and  rubber  tubes  were 
chloride  cleaned  in  the  usual  way,  and  kept  in  a brine 
ondsait.  solution  containing  5 per  cent  of  calcium  chlo- 
ride and  then  saturating  this  solution  with  common  salt. 

Even  though  the  parts  of  the  machine  were  well  washed 
and  kept  in  a sterile  solution  during  the  time  interven- 
ing the  milking,  the  germ  content  of  the  machine-milked 
milk  is  higher  than  that  obtained  by  hand-milking. 

Use  of  In  the  period  6 cotton  filtensi  were  placed  over  all 
cotton  intakes.  The  small  pneumatic  engine  on  the  top 
filters  of  the  pail  is  operated  by  suction.  Barn  air  is 
continuously  drawn  into  the  pail  in  the  form  of  exhaust 
from  this  engine  or  pulsator.  This  barn  air  contains  a 
large  number  of  germs  and  evidently  is  one  of  the  chief 
sources  of  the  relatively  large  germ  content  of  milk  drawn 
by  the  milking  machine. 

To  overcome  this,  cotton  filters  were  placed  over  all  of 
the  air  inlets  to  the  pail.  One  filter  used  was  made  by 
using  a small  funnel  filled  with  non-absorbent  cotton. 
(Cheesecloth  was  tied  over  the  mouth  of  the  funnel.  With 
a small  piece  of  rubber  tubing  this  funnel  filter  was  fast- 
ened to  the  small  extensoin  air  tubes  on  the  pneumatic 
engine.  Since  the  small  air-vents  in  the  engine  have  no 
extension,  they  were  supplied  with  filters  by  fastening  a 
suitable  thickness  of  cotton  filter  wrapped  in  cheesecloth 
directly  over  the  opening. 

These  cotton  filters  reduced  the  bacterial  count  of 
the  milking  machine  milk  to  a considerable  extent.  The 
increase  of  the  bacterial  content  during  the  latter  part  of 
period  6 is  undoubtedly  due  to  the  filters  being  little  too 
loose.  Considerable  care  is  necessary  to  have  the  filter 
properly  made.  It  must  not  be  iso  firm  as  not  to  [>ermit 
the  proper  amount  of  air  to  pass  through,  and  thus  inter- 
fere with  the  proper  work  of  the  pulsator,  and  yet  it  must 
be  sufficiently  packed  to  thoroughly  filter  the  air  and  re- 
tain the  dust  particles. 

From  these  studies,  it  is  clear  that  although  the  pail 


231 


'f,' 


of  the  milking  machine  is  covered  to  exclude  visible  dirt, 
the  constant  suction  of  barn  air  through  the  pneumatic 
/engine  or  pu  Isa  tor  into  the  pail  is  one  of  the  chief  sources 
of  the  large  number  of  germs  in  milk  drawn  by  the  milk- 
ing machine.  This  difficulty  may  be  partially  overcome 
by  filtering  the  air  through  properly  constructed  filters. 

Another  important  source  of  germ  content  of 
milk  drawn  by  milking  machine  is  the  condition 
cf  the  rubber  tubes  and  teat-cups.  The  trouble  from  this 
source  can  be  lessened  in  two  ways.  First,  all  the  rubber 
parts  should  be  well  cleaned  in  lukewarm  water  and  rinsed 
in  hot  water.  Steam  and  extremely  hot  water  shorten 
the  life  of  the  rubber.  Keeping  these  parts  in  a solution 
of  calcium-chloride  and  common  salt  between  milkings  is 
an  effective  method  of  handling  these  parts  in  a sanitary 
condition.  Second,  when  the  rubber  begins  to  crack  and 
check,  new  parts  should  be  secured.  Old  overheated  and 
cracked  rubber  is  sticky.  When  in  use  this  rubber  spreads 
and  allows  milk  to  enter  the  openings.  These  crevices  are 
difficult  to  properly  clean  and  become  a dangerous  source 
of  infection. 

SU.AIMARY. 

1.  Viewed  from  a mechanical  standpoint,  the  milk- 
ing machines  used  in  this  experiment  caused  very  little 
trouble  in  operating.  It  is  safe  to  conclude  that  with 
reasonable  care  this  type  of  milking  machine  can  be  success- 
fully and  profitably  oj)erated  on  the  average  farm  having 
at  least  twcnit}^  cowis. 

2.  Cows  giving  a large  flow  of  milk  were  easily  brok- 
en to  the  use  of  machine. In  general,  little  dilliculty  was 
experienced  in  getting  any  of  the  cows  accustomed  to  the 
milking  machine.  The  operator,  in  order  to  operate  most 
successfuly,  should  study  the  individuality  of  the  cows. 

3.  It  is  best  to  strip  the  cows  at  once  after  the  teat- 
cups  are  detached  to  make  sure  that  no  milk  remains. 
If  the  teat-cups  are  properly  attached  very  little  milk 
remains  in  tlie  udder  after  tlie  cow  is  milked  by  the  ma- 
chine. 


232 


4.  No  definite  statement  can  be  made  as  to  the  effect 
of  machine  milking  upon  milk  and  butter  fat  yield,  as  the 
experiments  have  not  extended  over  a sufficient  period  of 
time.  Results  of  these  experiments  indicate  that  if  the 
machine  and  cows  are  properly  handled,  the  amount  of  ' 
milk  and  butterfat  is  not  materially  affected  by  machine 
milking. 

5.  Milk  drawn  by  machine  was  free  from  sediment 
and  other  visible  impurities.  It,  however,  contained  more 
bacteria  than  did  the  milk  drawn  by  hand  into  a partially 
covered  pail. 

6.  The  barn  air  drawn  in  by  the  machine  proved 
an  important  soimce  of  contamination.  By  filtering  this 
air  through  cotton  filters  the  bacterial  content  of  the  ma- 
chine-milked milk  can  be  greatly  reduced. 

7.  The  germ  content  of  machine-milked  milk  can 
also  be  reduced  by  soaking  the  various  rubber  tubes  and 
teat-cups  in  an  antiseptic  solution.  A five  per  cent  solu- 
tion of  calcium-chloride  saturated  with  sodium-chloride 
proved  to  be  effective  in  these  experiments,  and  can  safely 
be  recommended. 


^ V3i 


